/*
    *  Licensed to the Apache Software Foundation (ASF) under one
    *  or more contributor license agreements.  See the NOTICE file
    *  distributed with this work for additional information
    *  regarding copyright ownership.  The ASF licenses this file
    *  to you under the Apache License, Version 2.0 (the
    *  "License"); you may not use this file except in compliance
    *  with the License.  You may obtain a copy of the License at
    *
   *    http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing,
   *  software distributed under the License is distributed on an
   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   *  KIND, either express or implied.  See the License for the
   *  specific language governing permissions and limitations
   *  under the License.
   *
   */
  
  package org.apache.mina.filter.firewall;
  
  import java.net.Inet4Address;
  import java.net.Inet6Address;
  import java.net.InetAddress;
  
  /**
   * A IP subnet using the CIDR notation. Currently, only IP version 4
   * address are supported.
   *
   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
   */
  public class Subnet {
  
      private static final int IP_MASK_V4 = 0x80000000;
  
      private static final long IP_MASK_V6 = 0x8000000000000000L;
  
      private static final int BYTE_MASK = 0xFF;
  
      private InetAddress subnet;
  
      /** An int representation of a subnet for IPV4 addresses */
      private int subnetInt;
  
      /** An long representation of a subnet for IPV6 addresses */
      private long subnetLong;
  
      private long subnetMask;
  
      private int suffix;
  
      /**
       * Creates a subnet from CIDR notation. For example, the subnet
       * 192.168.0.0/24 would be created using the {@link InetAddress}
       * 192.168.0.0 and the mask 24.
       * @param subnet The {@link InetAddress} of the subnet
       * @param mask The mask
       */
      public Subnet(InetAddress subnet, int mask) {
          if (subnet == null) {
              throw new IllegalArgumentException("Subnet address can not be null");
          }
  
          if (!(subnet instanceof Inet4Address) && !(subnet instanceof Inet6Address)) {
              throw new IllegalArgumentException("Only IPv4 and IPV6 supported");
          }
  
          if (subnet instanceof Inet4Address) {
              // IPV4 address
              if ((mask < 0) || (mask > 32)) {
                  throw new IllegalArgumentException("Mask has to be an integer between 0 and 32 for an IPV4 address");
              } else {
                  this.subnet = subnet;
                  subnetInt = toInt(subnet);
                  this.suffix = mask;
  
                  // binary mask for this subnet
                  this.subnetMask = IP_MASK_V4 >> (mask - 1);
              }
          } else {
              // IPV6 address
              if ((mask < 0) || (mask > 128)) {
                  throw new IllegalArgumentException("Mask has to be an integer between 0 and 128 for an IPV6 address");
              } else {
                  this.subnet = subnet;
                  subnetLong = toLong(subnet);
                  this.suffix = mask;
  
                  // binary mask for this subnet
                  this.subnetMask = IP_MASK_V6 >> (mask - 1);
              }
          }
      }
  
      /**
       * Converts an IP address into an integer
       */
      private int toInt(InetAddress inetAddress) {
         byte[] address = inetAddress.getAddress();
         int result = 0;
 
         for (int i = 0; i < address.length; i++) {
             result <<= 8;
             result |= address[i] & BYTE_MASK;
         }
 
         return result;
     }
 
     /**
      * Converts an IP address into a long
      */
     private long toLong(InetAddress inetAddress) {
         byte[] address = inetAddress.getAddress();
         long result = 0;
 
         for (int i = 0; i < address.length; i++) {
             result <<= 8;
             result |= address[i] & BYTE_MASK;
         }
 
         return result;
     }
 
     /**
      * Converts an IP address to a subnet using the provided mask
      * 
      * @param address
      *            The address to convert into a subnet
      * @return The subnet as an integer
      */
     private long toSubnet(InetAddress address) {
         if (address instanceof Inet4Address) {
             return toInt(address) & (int) subnetMask;
         } else {
             return toLong(address) & subnetMask;
         }
     }
 
     /**
      * Checks if the {@link InetAddress} is within this subnet
      * @param address The {@link InetAddress} to check
      * @return True if the address is within this subnet, false otherwise
      */
     public boolean inSubnet(InetAddress address) {
         if (address.isAnyLocalAddress()) {
             return true;
         }
 
         if (address instanceof Inet4Address) {
             return (int) toSubnet(address) == subnetInt;
         } else {
             return toSubnet(address) == subnetLong;
         }
     }
 
     /**
      * @see Object#toString()
      */
     @Override
     public String toString() {
         return subnet.getHostAddress() + "/" + suffix;
     }
 
     @Override
     public boolean equals(Object obj) {
         if (!(obj instanceof Subnet)) {
             return false;
         }
 
         Subnet"../../../../../org/apache/mina/filter/firewall/Subnet.html#Subnet">Subnet other = (Subnet) obj;
 
         return other.subnetInt == subnetInt && other.suffix == suffix;
     }
 
 }